org.corfudb.infrastructure

Class LayoutServer

java.lang.Object

org.corfudb.infrastructure.AbstractServer

org.corfudb.infrastructure.LayoutServer

public class LayoutServer
extends AbstractServer

The layout server serves layouts, which are used by clients to find the Corfu infrastructure.

For replication and high availability, the layout server implements a basic Paxos protocol. The layout server functions as a Paxos acceptor, and accepts proposals from clients consisting of a rank and desired layout. The protocol consists of three rounds:

1) Prepare(rank) - Clients first contact each server with a rank. If the server responds with ACK, the server promises not to accept any requests with a rank lower than the given rank. If the server responds with LAYOUT_PREPARE_REJECT, the server informs the client of the current high rank and the request is rejected.

2) Propose(rank,layout) - Clients then contact each server with the previously prepared rank and the desired layout. If no other client has sent a prepare with a higher rank, the layout is persisted, and the server begins serving that layout to other clients. If the server responds with LAYOUT_PROPOSE_REJECT, either another client has sent a prepare with a higher rank, or this was a propose of a previously accepted rank.

3) Committed(rank, layout) - Clients then send a hint to each layout server that a new rank has been accepted by a quorum of servers.

Created by mwei on 12/8/15.

Nested Class Summary

Nested classes/interfaces inherited from class org.corfudb.infrastructure.AbstractServer

AbstractServer.ServerState

Constructor Summary

Constructors

Constructor and Description
LayoutServer(ServerContext serverContext) Returns new LayoutServer for context.

Method Summary

Modifier and Type	Method and Description
Layout	getCurrentLayout()
ExecutorService	getExecutor()
Rank	getPhase1Rank()
org.corfudb.infrastructure.Phase2Data	getPhase2Data()
Rank	getPhase2Rank() Returns the phase 2 rank.
Layout	getProposedLayout() Returns the proposed layout received in phase 2 data.
void	handleMessageLayoutBootstrap(CorfuPayloadMsg<LayoutBootstrapRequest> msg, io.netty.channel.ChannelHandlerContext ctx, IServerRouter r) Sets the new layout if the server has not been bootstrapped with one already.
void	handleMessageLayoutCommit(CorfuPayloadMsg<LayoutCommittedRequest> msg, io.netty.channel.ChannelHandlerContext ctx, IServerRouter r) Accepts any committed layouts for the current epoch or newer epochs.
void	handleMessageLayoutPrepare(CorfuPayloadMsg<LayoutPrepareRequest> msg, io.netty.channel.ChannelHandlerContext ctx, IServerRouter r) Accepts a prepare message if the rank is higher than any accepted so far.
void	handleMessageLayoutPropose(CorfuPayloadMsg<LayoutProposeRequest> msg, io.netty.channel.ChannelHandlerContext ctx, IServerRouter r) Accepts a proposal for which it had accepted in the prepare phase.
void	handleMessageLayoutRequest(CorfuPayloadMsg<Long> msg, io.netty.channel.ChannelHandlerContext ctx, IServerRouter r) Handle a layout request message.
boolean	isServerReadyToHandleMsg(CorfuMsg msg)
void	setCurrentLayout(Layout layout) Sets the current layout in context DataStore.
void	setLayoutInHistory(Layout layout)
void	setPhase1Rank(Rank rank)
void	setPhase2Data(org.corfudb.infrastructure.Phase2Data phase2Data)

Methods inherited from class org.corfudb.infrastructure.AbstractServer

getHandler, getState, handleMessage, sealServerWithEpoch, setState, shutdown

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LayoutServer

public LayoutServer(@Nonnull
                    ServerContext serverContext)

Returns new LayoutServer for context.

Parameters:

serverContext - context object providing settings and objects

Method Detail

isServerReadyToHandleMsg

public boolean isServerReadyToHandleMsg(CorfuMsg msg)

Specified by:

isServerReadyToHandleMsg in class AbstractServer

getExecutor

public ExecutorService getExecutor()

Specified by:

getExecutor in class AbstractServer

handleMessageLayoutRequest

public void handleMessageLayoutRequest(CorfuPayloadMsg<Long> msg,
                                       io.netty.channel.ChannelHandlerContext ctx,
                                       IServerRouter r)

Handle a layout request message.

Parameters:

msg - corfu message containing LAYOUT_REQUEST

ctx - netty ChannelHandlerContext

r - server router

handleMessageLayoutBootstrap

public void handleMessageLayoutBootstrap(@NonNull
                                         CorfuPayloadMsg<LayoutBootstrapRequest> msg,
                                         io.netty.channel.ChannelHandlerContext ctx,
                                         @NonNull
                                         IServerRouter r)

Sets the new layout if the server has not been bootstrapped with one already.

Parameters:

msg - corfu message containing LAYOUT_BOOTSTRAP

ctx - netty ChannelHandlerContext

r - server router

handleMessageLayoutPrepare

public void handleMessageLayoutPrepare(@NonNull
                                       CorfuPayloadMsg<LayoutPrepareRequest> msg,
                                       io.netty.channel.ChannelHandlerContext ctx,
                                       @NonNull
                                       IServerRouter r)

Accepts a prepare message if the rank is higher than any accepted so far.

Parameters:

msg - corfu message containing LAYOUT_PREPARE

ctx - netty ChannelHandlerContext

r - server router

handleMessageLayoutPropose

public void handleMessageLayoutPropose(@NonNull
                                       CorfuPayloadMsg<LayoutProposeRequest> msg,
                                       io.netty.channel.ChannelHandlerContext ctx,
                                       @NonNull
                                       IServerRouter r)

Accepts a proposal for which it had accepted in the prepare phase. A minor optimization is to reject any duplicate propose messages.

Parameters:

msg - corfu message containing LAYOUT_PROPOSE

ctx - netty ChannelHandlerContext

r - server router

handleMessageLayoutCommit

public void handleMessageLayoutCommit(@NonNull
                                      CorfuPayloadMsg<LayoutCommittedRequest> msg,
                                      io.netty.channel.ChannelHandlerContext ctx,
                                      @NonNull
                                      IServerRouter r)

Accepts any committed layouts for the current epoch or newer epochs. As part of the accept, the server changes it's current layout and epoch.

Parameters:

msg - corfu message containing LAYOUT_COMMITTED

ctx - netty ChannelHandlerContext

r - server router

getCurrentLayout

public Layout getCurrentLayout()

setCurrentLayout

public void setCurrentLayout(Layout layout)

Sets the current layout in context DataStore.

Parameters:

layout - layout to set

getPhase1Rank

public Rank getPhase1Rank()

setPhase1Rank

public void setPhase1Rank(Rank rank)

getPhase2Data

public org.corfudb.infrastructure.Phase2Data getPhase2Data()

setPhase2Data

public void setPhase2Data(org.corfudb.infrastructure.Phase2Data phase2Data)

setLayoutInHistory

public void setLayoutInHistory(Layout layout)

getPhase2Rank

public Rank getPhase2Rank()

Returns the phase 2 rank.

Returns:

the phase 2 rank

getProposedLayout

public Layout getProposedLayout()

Returns the proposed layout received in phase 2 data.

Returns:

the proposed layout